Article Index

STx-Recorder | Real Time Frequency Analyser | Sound file Management | Sound file SegmentationVisualization | Frequency Analysis | Spectrograms | Quasi-continuous Wavelet-Transform | Wavelet-Phase-Diagram | Spectral Smoothing | Extraction of Formant Frequency Candidates (Speech) | Fundamental Frequency Analysis (Speech) | De-noising, Signal Enhancement | Auditory Perception Modeling | Simultaneous Masking | Order Analysis | STx Sequencer 

The STx Recorder

The STx Recorder is supplied with a peak programme meter. Digital recordings allow no overload at all. For that reason it is extremely important to adjust the signal input level to -12 dB in average, providing enough headroom for signal peaks.

Real Time Frequency Analyser (2-channel)

Sound file management

Sound file management, storage, archiving and migration of large sound files including metadata; DataSet management (xml-based)

Sound file segmentation and annotations (xml-based)


Visualization, labeling and annotation of sound data in the time domain, narrow segmentation (phonetic transcription, Unicode)


Frequency analysis (FFT, DFT,Wavelet, Filter Banks)


Spectrograms (FFT, Wavelet, Cepstrum, Linear Prediction Coding Formant Extraction) 

Visualization, labeling and annotation of time-varying signals by means of spectrograms (in the frequency domain)


Quasi-continuous Wavelet-Transform

and other time-frequency representations (Pseudo-Wigner-distribution).


Wavelet-Phase-Diagram:

Comparison of partial# 8 of 4 different music strings.


Spectral Smoothing

  1. Cepstrum Analysis: free selection of order (liftering)
  2. Linear Prediction Coding (LPC) Analysis: free selection of model order


Extraction of formant frequency candidates (in speech)


Fundamental Frequency Analysis (of speech signals)


De-noising, signal enhancement

spectral subtraction and frame averaging


Auditory perception modelling - (Computational Hearing)

Comparison of auditory model with LPC-model (for speech)


Simultaneous Masking - Over-Masking: spectral relevance


Order Analysis:

To identify gear orders in a multiple motor component environment a specific method for the generation of order spectrograms has been implemented. The method applies smoothing on the rpm-signal and uses re-sampling as well as the Discrete Fourier Transform (DFT) in combination with the anti aliasing filter to create order analysis spectrograms at reasonable computational cost.


STx Sequencer:

The spectrogram shows from left to right the real time filtering of white noise: Lowpass, Highpass, Bandpass and Bandstop

Basics in Sound Synthesis: STx-Sequencer.pdf